One of the problems which is encountered with the conventionally used railway car trucks is the rock and roll encountered due at least in part to the staggered rail joints generally used in the U.S.
Another problem is that of hunting or the tendency of the truck to oscillate resonantly about the center plate of the car body, due to dynamic instability.
It is preferred to solve the problems of rock and roll and hunting with a construction wherein the static height of the truck between empty and full loads is not too great and preferably not greater than about 21/2 inches. It further is desired that the railway car truck be capable of utilizing a standard wheel base, a standard center plate, and standard brakes.